This research will develop an optical instrument to aid in the noninvasive evaluation of skin affected by injury, surgical procedures and/or disease. The instrument will use characteristics of light absorption by hemoglobin species to delineate skin regions compromised by ischemia, hypoxia or necrosis. This research is based on the working hypothesis that reflectance spectra of pigments in skin provide information that can be used to locate and evaluate compromised regions of skin. During Phase I a skin imaging system will be constructed to obtain reflectance images at visible and near-infrared wavelengths from skin. Wavelengths will be chosen to monitor changes in hemoglobin absorption and tissue light scatter. Phase l studies will demonstrate feasibility of the working hypothesis using the rat pedicle skin flap as a model and provide design parameters for instruments to be constructed during Phase ll for clinical trials. During Phase lithe imaging system will undergo clinical testing to determine the system's ability to assist in the evaluation of vascular disorders, burns, wound healing and reconstructive surgery. The instrument will provide clinicians with a noncontact diagnostic method that is truly noninvasive and requires no injections or skin contact. It will provide rapid, easily interpreted image displays and be technically easy to use.